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pytorch-image-models/data/loader.py

129 lines
3.8 KiB

import torch.utils.data
from data.transforms import *
from data.distributed_sampler import OrderedDistributedSampler
def fast_collate(batch):
targets = torch.tensor([b[1] for b in batch], dtype=torch.int64)
batch_size = len(targets)
tensor = torch.zeros((batch_size, *batch[0][0].shape), dtype=torch.uint8)
for i in range(batch_size):
tensor[i] += torch.from_numpy(batch[i][0])
return tensor, targets
class PrefetchLoader:
def __init__(self,
loader,
rand_erase_prob=0.,
rand_erase_pp=False,
mean=IMAGENET_DEFAULT_MEAN,
std=IMAGENET_DEFAULT_STD):
self.loader = loader
self.mean = torch.tensor([x * 255 for x in mean]).cuda().view(1, 3, 1, 1)
self.std = torch.tensor([x * 255 for x in std]).cuda().view(1, 3, 1, 1)
if rand_erase_prob > 0.:
self.random_erasing = RandomErasing(
probability=rand_erase_prob, per_pixel=rand_erase_pp)
else:
self.random_erasing = None
def __iter__(self):
stream = torch.cuda.Stream()
first = True
for next_input, next_target in self.loader:
with torch.cuda.stream(stream):
next_input = next_input.cuda(non_blocking=True)
next_target = next_target.cuda(non_blocking=True)
next_input = next_input.float().sub_(self.mean).div_(self.std)
if self.random_erasing is not None:
next_input = self.random_erasing(next_input)
if not first:
yield input, target
else:
first = False
torch.cuda.current_stream().wait_stream(stream)
input = next_input
target = next_target
yield input, target
def __len__(self):
return len(self.loader)
@property
def sampler(self):
return self.loader.sampler
def create_loader(
dataset,
input_size,
batch_size,
is_training=False,
use_prefetcher=True,
rand_erase_prob=0.,
rand_erase_pp=False,
interpolation='bilinear',
mean=IMAGENET_DEFAULT_MEAN,
std=IMAGENET_DEFAULT_STD,
num_workers=1,
distributed=False,
crop_pct=None,
):
if isinstance(input_size, tuple):
img_size = input_size[-2:]
else:
img_size = input_size
if is_training:
transform = transforms_imagenet_train(
img_size,
interpolation=interpolation,
use_prefetcher=use_prefetcher,
mean=mean,
std=std)
else:
transform = transforms_imagenet_eval(
img_size,
interpolation=interpolation,
use_prefetcher=use_prefetcher,
mean=mean,
std=std,
crop_pct=crop_pct)
dataset.transform = transform
sampler = None
if distributed:
if is_training:
sampler = torch.utils.data.distributed.DistributedSampler(dataset)
else:
# This will add extra duplicate entries to result in equal num
# of samples per-process, will slightly alter validation results
sampler = OrderedDistributedSampler(dataset)
loader = torch.utils.data.DataLoader(
dataset,
batch_size=batch_size,
shuffle=sampler is None and is_training,
num_workers=num_workers,
sampler=sampler,
collate_fn=fast_collate if use_prefetcher else torch.utils.data.dataloader.default_collate,
drop_last=is_training,
)
if use_prefetcher:
loader = PrefetchLoader(
loader,
rand_erase_prob=rand_erase_prob if is_training else 0.,
rand_erase_pp=rand_erase_pp,
mean=mean,
std=std)
return loader